Timing of Reproduction, Flower and Seed Yield in Marigold Species (Tagetes erecta L. and T. patula L.) as Influenced by Different Sowing Dates

Abstract

Sequential and open field planting at monthly intervals (starting from June to November) of two quantitatively short day marigold species (Tagetes species) was conducted. The results revealed that 50% yield could not be compensated due to differential accurnula- tion of heat degree days. The remaining 50% of the flower yield is differentially compensated either by increase in flower number (10%) or by reduction ill flower fresh weight (50%). The African marigold on an average accumulated 10% lower ADD compared to the French type. Genotypic differences in the accumulation of heat degree days by 38% and 15% at 50% flowering and post- flowering ill African and French types might have influenced the flower quality. The mean accumulated degree days were 10% more in French marigold species in comparison to the African marigold. Genotypic differences regarding the accumulated heat degree days at flowering and post-Ilowerlng stages were most important for quality flower production.